The invention relates to data transfer mechanisms, and in particular, to a software-based, high speed DataPipe for providing high speed and reliable data transfer between computers.
It is fairly obvious that data, in the process of being archived or transferred from one location to another, will pass through various phases where different operations such as compression, network transfer, storage, etc. will take place on it. There are essentially two approaches that can be taken when implementing such a transfer mechanism. One would be to split the archival process into sub-tasks, each of which would perform a specific function (e.g. Compression). This would then require copying of data between the sub-tasks, which could prove processor intensive. The other method would be to minimize copies, and have a monolithic program performing all of the archival functions. The downside to this would be loss of parallelism. A third alternative would of course be to use threads to do these tasks and use thread-signaling protocols, however, it is realized that this would not be entirely practical since threads are not fully supported on many computing platforms.
Accordingly, it is highly desirable to obtain a high-speed data transfer mechanism implemented in software and developed for the needs of high speed and reliable data transfer between computers.
It is an object of the invention to disclose the implementation of the DataPipe in accordance with CommVault System""s Vault98 backup and recovery product. While developing the DataPipe, it is assumed that data, as it moves from archiving source (backup client) to archiving destination (backup server as opposed to media), may undergo transformation or examination at various stages in between. This may be to accommodate various actions such as data compression, indexing, object wrapping etc. that need to be performed on data being archived. Another assumption is the data may be transmitted over the network to remote machines or transferred to a locally attached media for archival.
Both the sending and the receiving computers execute software referred to herein as the DataPipe. Although the DataPipe transfer mechanism to be described herein is operative as a key component of backup and recovery software product schemes, the DataPipe is not restricted to that use. It is a general purpose data transfer mechanism implemented in software that is capable of moving data over a network between a sending and a receiving computer at very high speeds and in a manner that allows full utilization of one or more network paths and the full utilization of network bandwidth. A DataPipe can also be used to move data from one storage device to another within a single computer without the use of a network. Thus, the DataPipe concept is not confined to implementation only in networked systems, but is operable to transfer data in non-networked computers as well.
It is an object of the invention to provide in a communications system having an origination storage device and a destination storage device, a data transfer pipeline apparatus for transferring data in a sequence of N stages, where N is a positive integer greater than 1, from the origination to the destination storage device. The apparatus comprises dedicated memory having a predetermined number of buffers dedicated for carrying data associated with the transfer of data from the origination device or process to the destination device or process; and master control module for registering and controlling processes associated with the data transfer apparatus for participation in the N stage data transfer sequence. The processes include at least a first stage process for initiating the data transfer and a last Nth stage process for completing data transfer. The first stage process is operative to allocate a buffer from the predetermined number of buffers available within the dedicated memory for collection, processing, and sending of the data from the origination device to a next stage process. The last Nth stage process is operative to receive a buffer allocated to the first stage process from the (Nxe2x88x921)th stage process in the data transfer sequence and to free the buffer upon processing completion and storage in the destination device to permit reallocation of the buffer. The master control process further includes a means for monitoring the number of buffers from the pool of buffers allocated or assigned to particular processes in the pipeline, wherein the monitor means is operative to prevent allocation of further buffers to a particular process when the number of buffers currently allocated exceeds a predetermined threshold.